Advertisements say that certain compounds will prevent scale on boilers,
and I think they tell the truth, as far as they go; but they don't say
what the result may be on iron. I will not advise the use of any of
these preparations, for several reasons. In the first place, certain
chemicals will successfully remove the scale formed by water charged
with bicarbonate of lime, and have no effect on water charged with
sulphate of lime. Some kinds of bark-summac, logwood, etc.,-are
sufficient to remove the scale from water charged with magnesia or
carbonate of lime, but they are injurious to the iron owing to the
tannic acid with which they are charged. Vinegar, rotten apples, slop,
etc., owing to their containing acetic acid, will remove scale, but this
is even more injurious to the iron than the barks. Alkalies of any
kind, such as soda, will be found good in water containing sulphate of
lime, by converting it into a carbonate and thereby forming a soft
scale, which is easily washed out; but these have their objections, for,
when used to excess, they cause foaming.
Petroleum is not a bad thing in water where sulphate of lime prevails;
but you should use only the refined, as crude oil sometimes helps to
form a very injurious scale. Carbonate of soda and corn-starch have been
recommended as a scale preventative, and I am inclined to think they are
as good as anything, but as we are out in the country most of the time I
can tell you of a simple little thing that will answer the same purpose,
and can usually be had with little trouble. Every Monday morning just
dump a hatful of potatoes into your boiler, and Saturday night wash the
boiler out, as I have already suggested, and when the fall's run is over
there will not be much scale in the boiler.